I am new to grafting myself and bought pots this year for all my rootstock (I also had a collection of miscellaneous pots that I have collected over the years as well that were used) so not sure about putting them in the ground until theybare in there permanent spot 
someone with more experience in this matter should answer you with that question, like @thepodpiper 
Here is a link to my similar thread to this one Here
That thread will let you know where I am at with my Orchard and my projects @JohnnyRoger